Transfer arm

ABSTRACT

A conveying arm of the invention includes a first pivotable shaft connected to a first arm which is also pivotably connected to a third arm having an intermediate pivotable portion. The third arm is also pivotably connected to a fifth arm which is also pivotably connected to a seventh arm which has a holding portion for an object to be conveyed. The conveying arm also includes a second pivotable shaft connected to a second arm which is also pivotably connected to a fourth arm having an intermediate pivotable portion. The fourth arm is also pivotably connected to a sixth arm which is also pivotably connected to the seventh arm. With respect to both the third and fourth arms, a line linking one-side end portion to an intermediate pivotable portion is substantially perpendicular to a line linking the other-side end portion to the intermediate pivotable portion.

FIELD OF THE INVENTION

This invention relates to a conveying arm that can be miniaturized andthat is superior in characteristics of control.

BACKGROUND OF THE INVENTION

Conventionally, when a semiconductor substrate such as a semiconductorwafer (that can be abbreviated to “wafer”) is conveyed between acassette that can accommodate the wafer and a semiconductormanufacturing unit or between various semiconductor manufacturing units,a conveying arm that forms a conveying unit is used.

A multi-chamber type of processing unit is explained as an example,which is also a cluster type of unit. In the case, a conveying arm isaccommodated in a transfer-chamber (common transfer-chamber). Theconveying arm has a substrate holding portion. The substrate holdingportion is formed in such a manner that the substrate holding portioncan be moved into not only the transfer-chamber but also variousprocess-chambers or a cassette-chamber that are connected to thetransfer-chamber. Thus, when the conveying arm is operated, anunprocessed wafer can be conveyed from a cassette in thecassette-chamber to any of the process-chambers through thetransfer-chamber. In addition, when the conveying arm is operated, aprocessed wafer can be conveyed back from any of the process-chambers tothe cassette through the transfer-chamber.

As the conveying arm, a scalar-type of conveying arm and a frog-leg typeof conveying arm are used in general.

The scalar-type of conveying arm has two or more arms that connect asubstrate holding portion and a pivotable shaft. A pivoting mechanism isconnected to the pivotable shaft and respective pivotable portions ofthe arms, for example via one or more rotating belts and one or morepulleys. Thus, when the pivotable shaft is operated, the arms can extendor retract in a horizontal direction and the substrate holding portioncan be moved to predetermined positions.

On the other hand, the frog-leg type of conveying arm has a plurality offrog-leg arms, each of which consists of a pair of arms that areconnected with each other substantially in a frog-leg manner. Theplurality of frog-leg arms connects a substrate holding portion and apivotable shaft. A pivoting-power transmitting mechanism is connected tothe pivotable shaft. When the pivotable shaft is operated, the pluralityof frog-leg arms can extend or retract in a radial direction from acenter of the pivot and the substrate holding portion can be moved topredetermined positions.

When the scalar type of conveying arm is adopted for the aboveprocessing unit, the rotating belts and the pulleys, which form thepivoting mechanism, have to be disposed in the transfer-chamber throughwhich the wafer is moved. Thus, when the conveying arm is operated,particles may tend to be generated. The particles may easily contaminatethe wafers and may deteriorate a yield of the wafers.

In addition, in the scalar type of conveying arm, vibrations may tend tobe generated because the scalar type of conveying arm has the rotatingbelts and the pulleys. Thus, it is difficult to raise a conveying speed.

When the frog-leg type of conveying arm is adopted for the aboveprocessing unit, the above rotating belts or pulleys generally need notbe disposed in the transfer-chamber. Thus, it can be prevented orinhibited that particles are generated and that vibrations aregenerated. Thus, it is possible to raise a conveying speed.

However, because of the structure itself of the frog-leg type ofconveying arm, an end portion of the arms connected to the substrateholding portion can not retract in a radial direction of a sidesubstantially opposite to the substrate holding portion with respect tothe center of the pivot of the whole conveying arm. That is, there is alimitation to enlarge an extending/retracting distance, in which theconveying arm can extend and retract, with respect to a pivoting radiusof the conveying arm. Thus, when the center of the pivot is away from aposition to which a wafer should be moved, the conveying arm has to beproportionally enlarged. Therefore, it is impossible that the unitadopting the conveying arm is miniaturized.

In addition, if the substrate holding portion is arranged further awayfrom the center of the pivot, the substrate holding portion is subjectedto a larger centrifugal force when the conveying arm is pivoted. Thus,because of the centrifugal force and/or vibrations caused by thecentrifugal force, the wafer placed on the substrate holding portion maybe moved out from a predetermined position or may even fall down.

In addition, in both of the scalar type of conveying arm and thefrog-leg type of conveying arm, a resolution in a state wherein theconveying arm relatively contracts is very different from a resolutionin another state wherein the conveying arm relatively extends. That is,when the conveying arm is caused to extend or contract in the statewherein the conveying arm relatively contracts, a resolution by whichthe substrate holding portion is moved in a radial direction isrelatively high. On the other hand, when the conveying arm is caused toextend or contract in the state wherein the conveying arm relativelyextends, a resolution by which the substrate holding portion is moved inthe radial direction is relatively low. Thus, it is difficult to exactlyconvey a wafer placed on the substrate holding portion to apredetermined position. In particular, if the conveying arm is operatedat a higher speed, it becomes more difficult to precisely convey thewafer.

SUMMARY OF THE INVENTION

This invention is intended to solve the above problems in the prior art.The object of this invention is to provide a new and improved conveyingarm in which an extending/retracting distance with respect to a pivotingradius of the conveying arm is large and a resolution in a state whereinthe conveying arm relatively contracts is substantially the same as aresolution in another state wherein the conveying arm relativelyextends.

In order to achieve the above object, a conveying arm according to theinvention comprises: a first pivotable shaft; a first arm having aone-side end portion connected to the first pivotable shaft; a third armhaving an intermediate pivotable portion and a one-side end portionpivotably connected to an other-side end portion of the first arm; afifth arm having a one-side end portion pivotably connected to another-side end portion of the third arm; a second pivotable shaft; asecond arm having a one-side end portion connected to the secondpivotable shaft; a fourth arm having an intermediate pivotable portionpivotably connected to the intermediate pivotable portion of the thirdarm and a one-side end portion pivotably connected to an other-side endportion of the second arm; a sixth arm having a one-side end portionpivotably connected to an other-side end portion of the fourth arm; anda seventh arm having a holding portion for an object to be conveyed,pivotably connected to an other-end portion of the fifth arm and another-end portion of the sixth arm; wherein a positional relationshipbetween the one-side end portion of the third arm, the intermediatepivotable portion of the third arm and the other-side end portion of thethird arm is in such a manner that a line linking the one-side endportion to the intermediate pivotable portion is substantiallyperpendicular to a line linking the other-side end portion to theintermediate pivotable portion, and a positional relationship betweenthe one-side end portion of the fourth arm, the intermediate pivotableportion of the fourth arm and the other-side end portion of the fourtharm is in such a manner that a line linking the one-side end portion tothe intermediate pivotable portion is substantially perpendicular to aline linking the other-side end portion to the intermediate pivotableportion.

As another feature of the invention, the other-side end portion of thethird arm and the other-side end portion of the fourth arm are in a sameside as the first pivotable shaft and the second pivotable shaft withrespect to the respective intermediate pivotable portions.

Preferably, the third arm and the fourth arm have shapes substantiallysymmetric with respect to each other. In particular, it is preferablethat the third arm and the fourth arm are substantially L-shaped arms.

In addition, it is preferable that the first arm and the second arm havea substantially same length. In addition, it is preferable that thefifth arm and the sixth arm have a substantially same length.

If the first pivotable shaft and the second pivotable shaft are adaptedto be independently pivoted around a same axis, a pivoting movement ofthe holding portion for an object to be conveyed can be achieved bypivoting the first pivotable shaft and the second pivotable shaft in asame direction. In addition, in the case, a linear movement of theholding portion for an object to be conveyed can be achieved by pivotingthe first pivotable shaft and the second pivotable shaft in oppositedirections.

If the first pivotable shaft and the second pivotable shaft are adaptedto be pivoted around separate axes, the first pivotable shaft and thesecond pivotable shaft are adapted to be pivoted in opposite directionsthrough a same angle. In addition, preferably, the first pivotable shaftand the second pivotable shaft are provided on a driving mechanism thatcan pivot the whole conveying arm.

In addition, the fifth arm and the sixth arm are adapted to be pivotedwith respect to the seventh arm in such a manner that an angle formed bythe fifth arm and the seventh arm is always equal to an angle formed bythe sixth arm and the seventh arm.

In addition, in order to achieve the above object, another conveying armaccording to the invention comprises: a guide extending in asubstantially straight manner; a first slider and a second slider thatcan slide along the guide; a third arm having an intermediate pivotableportion and a one-side end portion pivotably connected to the firstslider; a fifth arm having a one-side end portion pivotably connected toan other-side end portion of the third arm; a fourth arm having anintermediate pivotable portion pivotably connected to the intermediatepivotable portion of the third arm and a one-side end portion pivotablyconnected to the second slider; a sixth arm having a one-side endportion pivotably connected to an other-side end portion of the fourtharm; and a seventh arm having a holding portion for an object to beconveyed, pivotably connected to an other-end portion of the fifth armand an other-end portion of the sixth arm; wherein a positionalrelationship between the one-side end portion of the third arm, theintermediate pivotable portion of the third arm and the other-side endportion of the third arm is in such a manner that a line linking theone-side end portion to the intermediate pivotable portion issubstantially perpendicular to a line linking the other-side end portionto the intermediate pivot able portion, and a positional relationshipbetween the one-side end portion of the fourth arm, the intermediatepivotable portion of the fourth arm and the other-side end portion ofthe fourth arm is in such a manner that a line linking the one-side endportion to the intermediate pivotable portion is substantiallyperpendicular to a line linking the other-side end portion to theintermediate pivotable portion.

In the case, a movement of the holding portion for an object to beconveyed in a direction parallel to the guide can be achieved by movingthe first slider and: the second slider in a same direction, and amovement of the holding portion for an object to be conveyed in adirection substantially perpendicular to the guide can be achieved bymoving the first slider and the second slider in opposite directions.

In the above intention as well, as another feature, the other-side endportion of the third arm and the other-side end portion of the fourtharm are in a same side as the guide with respect to the respectiveintermediate pivotable portions.

In the above invention as well, preferably, the third arm and the fourtharm have shapes substantially symmetric with respect to each other. Inparticular, it is preferable that the third arm and the fourth arm aresubstantially L-shaped arms. In addition, it is preferable that thefirst arm and the second arm have a substantially same length. Inaddition, the fifth arm and the sixth arm are adapted to be pivoted withrespect to the seventh arm in such a manner that an angle formed by thefifth arm and the seventh arm is always equal to an angle formed by thesixth arm and the seventh arm.

According to the invention, an end portion of the seventh arm in a sideof the fifth arm and the sixth arm can be moved over a center of thepivot of the conveying arm, that is, can retract over the center of thepivot in a direction substantially opposite to an extending direction ofthe holding portion for an object to be conveyed. Thus, anextending/retracting distance of the conveying arm can be enlargedwithout increasing a pivoting radius of the conveying arm. Thus, theconveying arm can be miniaturized, and a unit accommodating theconveying arm can be miniaturized.

In addition, when the conveying arm is caused to retract, a center ofthe holding portion for an object to be conveyed and the center of thepivot of the conveying arm can be substantially equal or close to eachother. Thus, even when the conveying arm is pivoted while an object tobe conveyed is mounted on the holding portion for an object to beconveyed, the object to be conveyed may not be subjected to a too largecentrifugal force. Thus, it can be prevented that the object to beconveyed is moved out from a prescribed position on the holding portionfor an object to be conveyed or that the object to be conveyed fallsdown from the holding portion for an object to be conveyed.

In addition, since the third arm and the fourth arm whose intermediatepivotable portions are connected with each other are adopted, aresolution of the movement (an extending/contracting rate) of theconveying arm in a state wherein the conveying arm relatively contractsmay be substantially equal to a resolution of the movement in anotherstate wherein the conveying arm relatively extends. Thus, wherever theholding portion for an object to be conveyed is arranged, it may becomeeasy to exactly convey an object to be conveyed placed on the holdingportion for an object to be conveyed to a predetermined position. Inaddition, even if the conveying arm is operated at a higher speed,operational performance of the conveying arm may not be deteriorated andthe conveying arm can be controlled easily and surely.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic perspective view of a first embodiment of aconveying arm according to the invention;

FIG. 2 is a schematic perspective view of a third arm and a fourth armshown in FIG. 1;

FIG. 3 is a schematic front view of the third arm and the fourth armshown in FIG. 1;

FIG. 4 is a schematic explanatory view for explaining a seventh armshown in FIG. 1;

FIGS. 5a and b are a schematic explanatory view for showing an operationof the conveying arm shown in FIG. 1;

FIGS. 6a and b are another schematic explanatory view for showing theoperation of the conveying arm shown in FIG. 1;

FIGS. 7a and b are another schematic explanatory view for showing theoperation of the conveying arm shown in FIG. 1;

FIG. 8 is a schematic perspective view of a second embodiment of aconveying arm according to the invention;

FIGS. 9a and b are a schematic explanatory view for showing an operationof the conveying arm shown in FIG. 8;

FIGS. 10a-c are a schematic explanatory view for showing another drivingmechanism applicable to the conveying arms shown in FIG. 1 and FIG. 8;

FIGS. 11a-c are a schematic explanatory view for showing another drivingmechanism applicable to the conveying arms shown in FIG. 1 and FIG. 8;

FIG. 12 is a schematic plan view of a third embodiment of a conveyingarm according to the invention; and

FIG. 13 is a schematic plan view of a fourth embodiment of a conveyingarm according to the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Embodiments of the invention will now be described in more detail withreference to accompanied drawings. In each of the embodiments, theinvention is applied to a conveying arm for a semiconductor substrate.

A conveying arm 100 of a first embodiment is explained with reference toFIGS. 1 to 7. At first, a whole structure of the conveying arm 100 isexplained.

As shown in FIGS. 1 to 3, a first pivotable shaft 104 is fixed to aone-side end portion of a first arm 102. A second pivotable shaft 108 isfixed to a one-side end of a second arm 106.

In the case, as shown in FIGS. 1 to 3, the first pivotable shaft 104 andthe second pivotable shaft 108 arc formed to have the same axis. Thatis, the second pivotable shaft 108 is tubular, and the first pivotableshaft 104 is inserted into a hollow portion of the second pivotableshaft 108. A center of a pivot of the first pivotable shaft 104 and acenter of a pivot of the second pivotable shaft 108 are arranged in thesame axis. In addition, as shown in FIG. 5(b), the first pivotable shaft104 is connected to a first driving mechanism 138 such as a servomotor,and the second pivotable shaft 108 is connected to a second drivingmechanism 140.

In addition, as shown in FIGS. 1 to 3, an other-side end portion of thefirst arm 102 and a one-side end portion of a third arm 110 arepivotably connected to each other via a first joint 112. The third arm110 bends at an intermediate pivotable portion 118 a thereof and issubstantially L-shaped. An other-side end portion of the second arm 106and a one-side end portion of a fourth arm 114 are pivotably connectedto each other via a second joint 116. The fourth arm 114 bends at anintermediate pivotable portion 118 b thereof and is substantiallyL-shaped.

A line linking the one-side end portion of the third arm 110 to theintermediate pivotable portion of the third arm 110 is substantiallyperpendicular to a line linking the other-side end portion of the thirdarm 110 to the intermediate pivotable portion of the third arm 110. Inaddition, a line linking the one-side end portion of the fourth arm 114to the intermediate pivotable portion of the fourth arm 114 is alsosubstantially perpendicular to a line linking the other-side end portionof the fourth arm 114 to the intermediate pivotable portion of thefourth arm 114.

The intermediate pivotable portion 118 a of the third arm 110 and theintermediate pivotable portion 118 b of the fourth arm 114 are pivotablyconnected to each other via a third joint 118. In the case, as shown inFIG. 3, the third joint 118 passes through the third arm 110 and joinstwo divided portions of fourth arm 114. That is, the third arm 110 andthe fourth arm 114 intersect in a vertical plane. Thus, a height of afifth arm 120 and a height of a sixth arm 124 are adjusted to be thesame. In the shown example, a bending angle of the third arm 110 and abending angle of the fourth arm 114 are 90 degrees, respectively.

The first arm 102 and the second arm 106 have a substantially samelength. In addition, the fifth arm 120 and the sixth arm 124 have asubstantially same length.

In addition, the other-side end portion of the third arm 110 and aone-side end portion of the fifth arm 120 are pivotably connected toeach other via a fourth joint 122. The other-side end portion of thefourth arm 114 and a one-side end portion of the sixth arm 124 arepivotably connected to each other via a fifth joint 126. In addition,the other-side end portion of the fifth arm 120 and the other-side endportion of the sixth arm 124 are pivotably connected to a one-side endportion of a seventh arm 132 via a corresponding sixth joint 128 and acorresponding seventh joint 130, respectively.

As shown in FIG. 4, a gear portion 120 a is formed at an end area of thefifth arm 120 on a side of the sixth joint 128. A gear portion 124 a isalso formed at an end area of the sixth arm 124 on a side of the seventhjoint 130. The fifth arm 120 and the sixth arm 124 are attached to theseventh arm 132 in such a manner that the gear portion 120 a and thegear portion 124 a are engaged with each other. In the case, the seventharm 132 is arranged to divide an angle formed by the fifth arm 120 andthe sixth arm 124 into two substantially equal angles. Even if the gearportion 120 a and the gear portion 124 a roll and move, a relationshipwherein the seventh arm 132 is located to divide the angle formed by thefifth arm 120 and the sixth arm 124 into two substantially equal anglesmay be maintained. In the example shown in FIG. 1, each of the first toseventh joints 112, 116, 118, 122, 126, 128 and 130 pivotably links therespective arms via a pivotable shaft extending in a vertical direction.

A fork-like substrate holding portion 132 a is formed at the seventh arm132, as a holding portion for an object to be conveyed. In the shownexample, the seventh arm 132 and the substrate holding portion 132 a areformed in one unity. In addition, holding pins 134 are provided on aplacing surface of the substrate holding portion 132 a in order to holda wafer W as an object to be conveyed. The respective arms 102, 106,110, 114, 120, 124 and 132 are made of aluminum, ceramics or the like.

The first arm 102, the second arm 106, the third arm 110 and the fourtharm 114 are arranged in such a manner that distances between any two ofrespective pivotable shafts of the first pivotable shaft 104, the firstjoint 112, the second joint 116 and the third joint 118 aresubstantially the same. That is, the first arm 102, the second arm 106,a section of the third arm 110 from the one-side end portion to theintermediate pivotable portion 118 a and a section of the fourth arm 114from the one-side end portion to the intermediate pivotable portion 118b are arranged to form a substantially lozenge.

With respect to the fifth arm 120 and the sixth arm 124, the fifth arm120, the sixth arm 124, a section of the third arm 110 from theintermediate pivotable portion 118 a to the other-side end portion and asection of the fourth arm 114 from the intermediate pivotable portion118 b to the other-side end portion are arranged to form a substantiallylozenge.

In addition, the conveying arm 110 is mounted on a base 136.

Then, a conveying operation of the conveying arm 100 is explained withreference to FIGS. 5 to 7. FIG. 5 shows a state wherein the conveyingarm 100 retracts. FIG. 6 shows a state wherein the conveying arm 100 ison extending. FIG. 7 shows a state wherein the conveying arm 100extends.

At first, when the conveying arm 100 is caused to extend from the statewherein the conveying arm 100 retracts as shown in FIGS. 5(a) and (b),the first driving mechanism 138 and the second driving mechanism 140operate to pivot the first pivotable shaft 104 and the second pivotableshaft 108. In the case, the first pivotable shaft 104 is pivoted in acounterclockwise direction, and the second pivotable shaft 108 ispivoted in a clockwise direction. In addition, the first pivotable shaft104 and the second pivotable shaft 108 are pivoted through the sameangle.

According to the above operation, as shown in FIGS. 6(a) and (b), anangle formed by the first arm 102 and the second arm 106 becomes narrow.In addition, an angle formed by the section of the third arm 110 of aside of the first joint 112 with respect to the intermediate pivotableportion 118a and the section of the fourth arm 114 of a side of thesecond joint 116 with respect to the intermediate pivotable portion 118b also becomes narrow. That is, the third joint 118 (a connectingportion of the third arm 110 and the fourth arm 114) is moved away fromthe centers of the pivots of the first pivotable shaft 104 and thesecond pivotable shaft 108.

In addition, an angle formed by the section of the third arm 110 of aside of the fourth joint 122 with respect to the intermediate pivotableportion 118 a and the fifth arm 120 also becomes narrow. In addition, anangle formed by the section of the fourth arm 114 of a side of the fifthjoint 126 with respect to the intermediate pivotable portion 118 b andthe sixth arm 124 also becomes narrow. As a result, the substrateholding portion 132 a is pushed out in a radius direction from thecenters of the pivots.

When the first pivotable shaft 104 and the second pivotable shaft 108are further pivoted, as shown in FIGS. 7(a) and (b), the angle formed bythe first arm 102 and the second arm 106, the angle formed by thesection of the third arm 110 of the side of the first joint 112 and thesection of the fourth arm 114 of the side of the second joint 116, theangle formed by the section of the third arm 110 of the side of thefourth joint 122 and the fifth arm 120 and the angle formed by thesection of the fourth arm 114 of the side of the fifth joint 126 and thesixth arm 124 become narrower respectively. As a result, the substrateholding portion 132 a is moved further away from the centers of thepivots.

On the other hand, when the conveying arm 100 is caused to retract fromthe state wherein the conveying arm 100 extends as shown in FIGS. 7(a)and (b), the first pivotable shaft 104 is pivoted in the clockwisedirection, and the second pivotable shaft 108 is pivoted in thecounterclockwise direction. In the case as well, the first pivotableshaft 104 and the second pivotable shaft 108 are pivoted through thesame angle. According to the above operation, as shown in FIGS. 6(a) and(b), the angle formed by the first arm 102 and the second arm 106, theangle formed by the section of the third arm 110 of the side of thefirst joint 112 and the section of the fourth arm 114 of the side of thesecond joint 116, the angle formed by the section of the third arm 110of the side of the fourth joint 122 and the fifth arm 120 and the angleformed by the section of the fourth arm 114 of the side of the fifthjoint 126 and the sixth arm 124 become wider respectively. As a result,the state shown in FIGS. 5(a) and (b) is achieved via the state shown inFIGS. 6(a) and (b). That is, the substrate holding portion 132 a ispulled back to the centers of the pivots.

As described above, the first arm 102 and the fifth arm 120 areconnected to each other via the substantially L-shaped third arm 110,the second arm 106 and the sixth arm 124 are connected to each other viathe substantially L-shaped fourth arm 114 and the intermediate pivotableportion 118 a of the third arm 110 and the intermediate pivotableportion 118 b of the fourth arm 114 are pivotably connected. Thus, whenthe conveying arm 100 is caused to retract, as shown in FIGS. 5(a) and(b), the seventh arm 132 can be retract oppositely to the extendingdirection with respect to the centers of the pivots. Thus, a movabledistance of the substrate holding portion 132 a can be enlarged withrespect to a pivoting radius of the conveying arm 100.

In addition, as described above, the fifth arm 120 and the sixth arm 124are engaged by the respective gear portions 120 a and 124 a. Thus, whenthe conveying arm 100 extends or retracts, the fifth arm 120 and thesixth arm 124 are pivoted in opposite directions through the same angle.Thus, the substrate holding portion 132 a can be moved together with theseventh arm 132 in a direction substantially dividing the angle formedby the fifth arm 120 and the sixth arm 124 into two equal angles.

In addition, in order to pivot the conveying arm 100, the firstpivotable shaft 104 and the second pivotable shaft 108 are pivoted inthe same direction through the same angle, respectively. Thus, theconveying arm 100 can be pivoted in a clockwise direction or in acounterclockwise direction. Thus, the extending/contracting direction ofthe substrate holding portion 132 a can be suitably changed. Inaddition, while the conveying arm 100 is pivoted, the substrate holdingportion 132 a may be subjected to only less centrifugal force, bymaintaining the state wherein the conveying arm 100 retracts.

In addition, if the first pivotable shaft 104 and the second pivotableshaft 108 are connected to an elevating mechanism not shown, theconveying arm 100 can be vertically moved up and down, that is, a heightof the substrate holding portion 132 a can be suitably adjusted.

In addition, an extending/contracting distance i.e. a resolution of themovement of the conveying arm 100 in the state wherein the conveying armcontracts may be substantially equal to an extending distance i.e. aresolution of the movement of the conveying arm 100 in the state whereinthe conveying arm extends. Thus, a position to which the substrateholding portion 132 a is moved can be controlled easily and exactly.

Then, a conveying arm 200 of a second embodiment is explained withreference to FIGS. 8 and 9. In the second embodiment, the same numeralreferences correspond to the same structures as the above conveying arm100. The explanation of the same structures is not repeated.

As shown in FIG. 8, in the conveying arm 200, the seventh arm 132 havingthe substrate holding portion 132 a is attached in a reverse orientationto the case of the above conveying arm 100. In addition, the section ofthe substantially L-shaped third arm 110 of the side of the fourth joint122 with respect to the intermediate pivotable portion 118 a is longerthan that in the conveying arm 100. Similarly, the section of thesubstantially L-shaped fourth arm 114 of the side of the fifth joint 126with respect to the intermediate pivotable portion 118 b is longer thanthat in the conveying arm 100. Other structure is substantially the sameas the above conveying arm 100.

According to the above structure, when the conveying arm 200 retracts,as shown in FIG. 9(a), similarly to the above conveying arm 100, theseventh arm 132 can be retract oppositely to the extending directionwith respect to the centers of the pivots of the first pivotable shaft104 and the second pivotable shaft 108.

In addition, when the conveying arm 200 extends, as shown in FIG. 9(b),an extending distance can be further enlarged than that in the conveyingarm 100.

In the conveying arm 200 of the second embodiment, as described above,the extending distance of the conveying arm 200 can be further enlarged.Thus, the movable distance of the substrate holding portion 132 a can befurther enlarged with respect to a pivoting radius of the conveying arm200.

In addition, similarly to the above conveying arm 100, a resolution ofthe movement of the conveying arm 200 in the state wherein the conveyingarm contracts may be substantially equal to a resolution of the movementof the conveying arm 200 in the state wherein the conveying arm extends.Thus, a position to which the substrate holding portion 132 a is movedcan be controlled easily and exactly.

In addition, in the conveying arm 200 of the second embodiment, pivotingportions tend to interfere with each other less than in the aboveconveying arm 100. Thus, a linking structure of the arms can be designedmore freely.

In the above two embodiments, the first pivotable shaft 104 and thesecond pivotable shaft 108 are pivoted around the same axis. However,this invention is not limited by the above structures.

For example, FIG. 10(a) shows a first pivotable shaft and a secondpivotable shaft in another conveying arm 300. FIG. 10(b) is a schematicsectional view taken along the A—A line of the FIG. 10(a). FIG. 10(c) isa schematic sectional view taken along the B—B line of the FIG. 10(a).

In the conveying arm 300 shown in FIGS. 10(a) to (c), the firstpivotable shaft 302 and the second pivotable shaft 304 are arranged insuch a manner that a center of a pivot of the first pivotable shaft 302and a center of a pivot of the second pivotable shaft 304 do not overlapwith each other (are not located in the same axis). In addition, thefirst pivotable shaft 302 and the second pivotable shaft 304 areconnected to each other via belts 306 and 307 that are respectivelywound in a substantially S-shaped manner or in a substantially reversedS-shaped manner. The first pivotable shaft 302 is connected to the firstarm 102 and a driving mechanism 308. The second pivotable shaft 304 isconnected to the second arm 106.

According to the above structure, since the first pivotable shaft 302and the second pivotable shaft 304 are connected to each other via thebelts 306 and 307, when the first pivotable shaft 302 is pivoted by thedriving mechanism 308, the second pivotable shaft 304 can be pivoted atthe same time. In addition, as shown in FIGS. 10(b) and (c), since thebelts 306 and 307 are attached in the substantially S-shaped manner orin the substantially reversed S-shaped manner, the first pivotable shaft302 and the second pivotable shaft 304 can be pivoted in oppositedirections through the same angle, respectively.

Then, FIG. 11(a) shows a first pivotable shaft and a second pivotableshaft in another conveying arm 400. FIG. 11(b) is a schematic sectionalview taken along the C—C line of the FIG. 11(a).

In the conveying arm 400 shown in FIGS. 11(a) and (b), a gear portion402 and a gear portion 404 are respectively formed at outsideperipheries of the first pivotable shaft 302 and the second pivotableshaft 304 that are explained with reference to FIGS. 10(a) to (c). Thegear portion 402 and the gear portion 404 are engaged with each other.

Alternatively, as shown in FIG. 11(c), correspondingly to a pivotingangle of the first pivotable shaft 302 and the second pivotable shaft304, a gear portion 500 and a gear portion 502 may be respectivelyformed only at a portion of the outside periphery of the first pivotableshaft 302 and a portion of the outside periphery of the second pivotableshaft 304, the gear portion 500 and the gear portion 502 being engagedwith each other. According to the structure, similarly, the firstpivotable shaft 302 and the second pivotable shaft 304 can be pivotedthrough a predetermined angle, respectively.

In each of the above structures, the driving mechanism 308 may beconnected to the second pivotable shaft 304, instead of to the firstpivotable shaft 302. In addition, each of the gear portions 402, 404,500 and 502 may be formed separately from the corresponding firstpivotable shaft 302 or second pivotable shaft 304.

Then, a conveying arm of a third embodiment of the invention isexplained with reference to FIG. 12. FIG. 12 is a schematic plan view ofthe conveying arm of the third embodiment.

As shown in FIG. 12, the conveying arm 20 of the third embodimentincludes a guide 10 extending in a substantially straight manner and afirst slider 11 and a second slider 12 that can slide along the guide10, instead of the first pivotable shaft, the second pivotable shaft,the first arm and the second arm. A one-side end portion of the thirdarm 110 is pivotably connected to the first slider 11. A one-side endportion of the fourth arm 114 is pivotably connected to the secondslider 12.

Other structure is substantially the same as the first embodiment shownin FIGS. 1 to 7. In the third embodiment, the same numeral referencescorrespond to the same structures as the first embodiment shown in FIGS.1 to 7. The explanation of the same structures is not repeated.

FIG. 12 shows two conveying arms 20. A upper conveying arm 20 is in anextending state, and a lower conveying arm 20 is in a contracting state.

In the third embodiment, when the first slider 11 and the second slider12 are moved in the same direction along the guide 10, a movement of thesubstrate holding portion 132 a in a direction along the guide 10 can beachieved.

In addition, when the first slider and the second slider are moved inopposite directions along the guide 10, a movement of the substrateholding portion 132 a in a direction substantially perpendicular to theguide 10 i.e. an extending/contracting movement can be achieved. Thus, asubstrate can be conveyed into or from a processing chamber P.

This embodiment can achieve a movement of the substrate holding portion132 a in a direction parallel to the guide 10, instead of the pivotingmovement of the substrate holding portion 132 a that can be achieved inthe above first and second embodiments.

According to the third embodiment, when the conveying arm 20 is causedto contract, the seventh arm 132 can be retract oppositely to theextending direction with respect to the guide 10. Thus, stability whenan object to be conveyed is moved along the guide 10 can be very good.

In addition, the substrate holding portion 132 a can be moved togetherwith the seventh arm 132 in a direction substantially dividing the angleformed by the fifth arm 120 and the sixth arm 124 into two equal angles.

In addition, an extending/contracting distance of the conveying arm 20in the state wherein the conveying arm contracts may be substantiallyequal to an extending/contracting distance of the conveying arm 20 inthe state wherein the conveying arm extends. Thus, a position to whichthe substrate holding portion 132 a is moved can be controlled easilyand exactly.

Then, a conveying arm of a fourth embodiment of the invention isexplained with reference to FIG. 13. FIG. 13 is a schematic plan view ofthe conveying arm of the fourth embodiment.

As shown in FIG. 13, in the conveying arm 30 of the fourth embodiment,the seventh arm 132 is attached in a reverse orientation to the case ofthe third embodiment. Other structure is substantially the same as thethird embodiment shown in FIG. 12. In the fourth embodiment, the samenumeral references correspond to the same structures as the thirdembodiment shown in FIG. 12. The explanation of the same structures isnot repeated.

According to the fourth embodiment, when the conveying arm 30 is causedto contract, the seventh arm 132 can be retract oppositely to theextending direction with respect to the center of the pivot. Thus,stability when an object to be conveyed is moved along the guide 10 canbe very good.

In the above embodiments, the seventh arm and the substrate holdingportion are formed in one unity. However, the seventh arm and thesubstrate holding portion are not limited by the manner, but could beformed separately.

A shape of the substrate holding portion 132 a is not limited by thefork-like shape, but could be suitably changed correspondingly to anobject to be conveyed or a unit for installing the conveying arm.

The preferable embodiments of the invention are explained with referenceto the accompanied drawings. However, the invention is not limited bythe embodiments, but could be changed or modified by persons skilled inthe art in a scope of claims.

What is claimed is:
 1. A conveying arm comprising; a first pivotableshaft; a first arm having a one-side end portion connected to the firstpivotable shaft; a third arm having an intermediate pivotable portionand a one-side end portion pivotably connected to an other-side endportion of the first arm; a fifth arm having a one-side end portionpivotably connected to an other-side end portion of the third arm; asecond pivotable shaft; a second arm having a one-side end portionconnected to the second pivotable shaft; a fourth arm having anintermediate pivotable portion pivotably connected to the intermediatepivotable portion of the third arm and a one-side end portion pivotablyconnected to an other-side end portion of the second arm; a sixth armhaving a one-side end portion pivotably connected to an other-side endportion of the fourth arm; and a seventh arm having a holding portionfor an object to be conveyed, pivotably connected to an other-endportion of the fifth arm and an other-end portion of the sixth arm;wherein a positional relationship between the one-side end portion ofthe third arm, the intermediate pivotable portion of the third arm andthe other-side end portion of the third arm is in such a manner that aline linking the one-side end portion to the intermediate pivotableportion is always substantially perpendicular to a line linking theother-side end portion to the intermediate pivotable portion, and apositional relationship between the one-side end portion of the fourtharm, the intermediate pivotable portion of the fourth arm and theother-side end portion of the fourth arm is in such a manner that a linelinking the one-side end portion to the intermediate pivotable portionis always substantially perpendicular to a line linking the other-sideend portion to the intermediate pivotable portion.
 2. A conveying armaccording to claim 1, wherein: the third arm and the fourth arm haveshapes substantially symmetric with respect to each other.
 3. Aconveying arm according to claim 1, wherein: the third arm and thefourth arm are substantially L-shaped arms.
 4. A conveying arm accordingto claim 1, wherein: the first arm and the second arm have asubstantially same length.
 5. A conveying arm according to claim 1,wherein: the fifth arm and the sixth arm have a substantially samelength.
 6. A conveying arm according to claim 1, wherein: the firstpivotable shaft and the second pivotable shaft are adapted to be pivotedaround separate axes.
 7. A conveying arm according to claim 6, wherein:the first pivotable shaft and the second pivotable shaft are adapted tobe pivoted in opposite directions through a same angle.
 8. A conveyingarm according to claim 7, wherein: the first pivotable shaft and thesecond pivotable shaft are provided on a driving mechanism that canpivot the whole conveying arm.
 9. A conveying arm according to claim 1,wherein: the fifth arm and the sixth arm are adapted to be pivoted withrespect to the seventh arm in such a manner that an angle formed by thefifth arm and the seventh arm is always equal to an angle formed by thesixth arm and the seventh arm.
 10. A conveying arm, wherein comprising:a first pivotable shaft; a first arm having a one-side end portionconnected to the first pivotable shaft; a third arm having anintermediate pivotable portion and a one-side end portion pivotablyconnected to an other-side end portion of the first arm; a fifth armhaving a one-side end portion pivotably connected to an other-side endportion of the third arm; a fourth arm having an intermediate pivotableportion pivotably connected to the intermediate pivotable portion of thethird arm and a one-side end portion pivotably connected to another-side end portion of the second arm; a sixth arm having a one-sideend portion pivotably connected to an other-side end portion of thefourth arm; and a seventh arm having a holding portion for an object tobe conveyed, pivotably connected to an other-end portion of the fiftharm and an other-end portion of the sixth arm; wherein a positionalrelationship between the one-side end portion of the third arm, theintermediate pivotable portion of the third arm and the other-side endportion of the third arm is in such a manner that a line linking theone-side end portion to the intermediate intermediate pivotable portionis substantially perpendicular to a line linking the other-side endportion to the intermediate pivotable portion, a positional relationshipbetween the one-side end portion of the fourth arm, the intermediatepivotable portion of the fourth arm and the other-side end portion ofthe fourth arm is in such a manner that a line linking the one-side endportion to the intermediate pivotable portion is substantiallyperpendicular to a line linking the other-side end portion to theintermediate pivotable portion, and the other-side end portion of thethird arm and the other-side end portion of the fourth arm are in a sameside as the first pivotable shaft and the second pivotable shaft withrespect to the respective intermediate pivotable portions.